Active knit compression garments, devices and related methods

ABSTRACT

Garments having active and passive knitted rows can provide desired levels of compression. Garments made of active and passive knitted rows can provide dynamic levels of compression with respect to both location and over time to address a variety of conditions.

PRIORITY CLAIM

The present application is a Continuation of U.S. application Ser. No.16/035,963, filed Jul. 16, 2018, which claims the benefit of U.S.Provisional Application No. 62/532,638 filed Jul. 14, 2017, and alsoclaims the benefit of U.S. Provisional Application No. 62/697,789, filedJul. 13, 2018, each of which is hereby fully incorporated herein byreference.

TECHNICAL FIELD

Embodiments relate to wearable devices that can produce compression indesired locations, patterns, and quantities of force for a variety ofapplications including promotion or inhibition of circulation, treatmentof anxiety-related disorders, and support or structural assistance suchas vertical loading.

BACKGROUND

Garments with compression features have been used for aesthetic reasons,for medical treatment, or for a combination of the two. Aesthetics canbe a key factor in adoption of a garment by consumers or by a patientwho would benefit from wearing a compression garment, as poor designleads to dissatisfaction and noncompliance. Even where no therapeuticlevel of compression is needed, “athleisure” clothing has becomepopular, including which garments that exhibit some compressive forceand are made to be stylish, form fitting, or shaping, as well ascomfortable. Examples include leggings or active footwear, for example.

Compression garments are worn articles of clothing that apply pressureto the body either through garment reduction (e.g., knit shapewear) orthrough inflation (e.g., a blood pressure cuff). Compression is aneffective medical treatment for disorders ranging from varicose veinsand lymphedema to orthostatic intolerance and deep vein thrombosis.Compression garments can promote or inhibit circulation, and they can beused in the treatment of anxiety related disorders or for support orstructural assistance (e.g., structural loading).

Conventional compression garments for medical use rely upon eitherunder-sized or inflatable compression technologies, whereas compressiongarments that are primarily intended for aesthetics are typicallyunder-sized and exhibit some elasticity. Under-sized elastic garmentsare typically associated with a particular portion of a user's body,such as a calf or forearm. The cross-section of the garment when relaxedis smaller than the cross-section of the portion of the body. Whenapplied, the garment stretches and exerts force as the elastic contractsback towards its relaxed size. Other types of non-elastic, undersizedcompression technologies include oversized garments that can be madeundersized by reducing the garment circumference after the garment hasbeen donned by adjustable mechanisms, such as lacing, buckles, hook andloop tape, or straps.

Under-sized garments apply a substantially constant pressure on theportion of the user's body at each particular point. Depending on theuser's anatomy, however, the amount of pressure can vary along thelength of the garment. Although under-sized garments can be designed toprovide substantially uniform pressure (or a desired pressure gradient)to a typical person, variations in user anatomy can result in variationfrom the intended pressure profile for that garment.

Furthermore, the pressure profile created by a garment can vary basedupon the way in which it is used. The cross-sections of various bodyparts change depending upon whether the person is seated, standing, orlying down. Therefore an under-sized garment, which typically cannot beresized or reshaped depending on the user's activity level or bodyposition, may apply different levels of compression for users withdifferent levels or types of activity.

SUMMARY

Garments made of active and passive knitted materials can providedesired levels of compression. Garments made of active and passiveknitted rows can provide dynamic levels of compression with respect toboth location and over time to address a variety of conditions.

The above summary is not intended to describe each illustratedembodiment or every implementation of the subject matter hereof. Thefigures and the detailed description that follow more particularlyexemplify various embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

Subject matter hereof may be more completely understood in considerationof the following detailed description of various embodiments inconnection with the accompanying figures, in which:

FIG. 1 depicts a passive fabric garment that is an under-sizedcompression garment.

FIG. 2 depicts a passive fabric garment that is a pneumatic compressiongarment.

FIG. 3 is a force-length diagram for a therapeutic compression garmentaccording to an embodiment.

FIGS. 4A and 4B are plan views of the fabric for a therapeuticcompression garment with weft knit active yarns in relaxed andcontracted states, respectively, according to an embodiment.

FIGS. 5A and 5B are plan views of the fabric for a therapeuticcompression garment with weft knit active and passive yarns in relaxedand activated states according to an embodiment.

FIGS. 6A-6C are plan views of the fabric for a therapeutic compressiongarment with fabric segments having active and passive sectionsaccording to three embodiments.

FIGS. 7A-7C are front, back, and side perspective views, respectively,of a therapeutic compression garment according to an embodiment.

FIG. 7D is a plan view of the garment of FIGS. 7A-7C.

FIG. 8 is a cross-sectional view of a portion of a multi-layertherapeutic compression garment according to an embodiment.

FIG. 9 is a force-length diagram for a self-fitting garment according toan embodiment.

FIGS. 10A-10C depict three styles of garments having positive ease, zeroease, and negative ease, respectively.

FIGS. 11A-11D depict a self-fitting garment that has approximately zeroease without the use of fasteners, according to an embodiment.

FIG. 12 depicts the required actuation contraction for a self-fittinggarment according to an embodiment.

FIG. 13 illustrates a flowchart of a method for providing a self-fittinggarment according to an embodiment.

FIGS. 14A and 14B depict load, actuation contraction, and mechanicalwork in a self-fitting garment by materials having a common knit index.

FIGS. 14C and 14D depict load, actuation contraction, and mechanicalwork in a self-fitting garment by materials having a second common knitindex.

FIGS. 15A and 15B depict load, actuation contraction, and mechanicalwork in a self-fitting garment by materials having a common diameter andvarying knit indices.

While various embodiments are amenable to various modifications andalternative forms, specifics thereof have been shown by way of examplein the drawings and will be described in detail. It should beunderstood, however, that the intention is not to limit the claimedinventions to the particular embodiments described. On the contrary, theintention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the subject matter as defined bythe claims.

DETAILED DESCRIPTION OF THE DRAWINGS

The following disclosure describes several different garments,materials, and knitting patterns that can be used to produce therapeuticgarments and aesthetically improved garments. Each of these garments isbased on interconnected loops of shape memory alloy material, which cantransition between a loose, flexible martensite state and an active,rigid austenite state. When loops of these material are knitted togetherthey form a functional fabric that contracts upon activation.

Functional fabrics of all types described herein can provide actuation,sensing, energy harvesting, and communication as intrinsic fabricproperties by integrating multifunctional fibers into designed textilegeometries. The fiber material and the textile architecture can bedesigned to achieve functional fabric characteristics such asdistributed actuation and sensing, variable stiffness, and complex,three-dimensional deformations. Through geometric design on themacroscopic and mesoscopic scales, knitted functional fabrics canachieve complex actuation deformations, such as corrugation, scrolling,and contraction. Additional, microscopic design parameters can beselected by the choice of multifunctional fiber and its specificmaterial properties. Specific patterns and materials can be used togenerate desired compression for either therapeutic, aesthetic, or otherfunctional purposes such as the elimination of traditional fastenersthat are required for non-compressive fabrics.

Throughout this disclosure, several specialized terms related to activeknitted fabrics are used. The first is “knit index,” which is the ratioof the area of a loop of active material enclosed in the martensitestate and the square of the active knit material wire diameter.Depending on the knit index among other factors, a functional fabricwith desired properties can be created. Two particularly importantproperties are the pressure applied by the fabric (i.e., how forcefullya garment made of the active fabric squeezes when the active material isactuated) and the actuation contraction of the fabric (i.e., thedistance in total length of the fabric when the active material isactuated). Actuation contraction of an active knit fabric is a functionof the martensite length l_(M) and the austenite length l_(A):

ζ=(l _(M) −l _(A))/l _(M),

Depending on the knit index, the diameter of the active material, andother factors, different types of active fabrics can be created. Onetype of fabric is referred to herein as a “therapeutic compressiongarment,” and it is designed primarily to provide a therapeutic level ofcompression to a wearer. Accordingly, the level of force applied by thefabric when activated should preferably reach a desired minimum level,while the total actuation contraction is of lesser importance.

A second type is referred to as a “self-fitting” garment, which is notintended to provide therapeutic compression but rather to contract to aaccurate fit for the wearer. Accordingly, the level of force applied bythe garment should be smaller than that of a therapeutic compressiongarment, while the total displacement should be larger.

Other garments, fabrics, or portions thereof can be made of “passive”material, which refers to materials that do not exhibit a shape-memorytransition.

Passive Fabric Compression Garments

FIGS. 1 and 2 relate to prior passive and active compression garmenttechnologies.

FIG. 1 shows an under-sized compression garment 100 applied to a user'scalf 102 and foot 104. When donned, under-sized compression garment 100applies pressure on calf 102 and foot 104 based upon the amount garment100 is stretched. As shown in FIG. 1, under-sized garment 100 is tubularin shape, with a circumference that varies along its length. Typically,under-sized garment 100 has an unstretched circumference that is smallerthan a body part that it is used with. Therefore in order to don thegarment 100, it is necessary to pre-stretch the garment 100. In morecomplex garments, pre-stretching the garment becomes more burdensome.For example, some garments are worn on parts of the body that aresmaller than the area they must pass over to be donned. In one example,a shirt must be stretched to pass over a user's head, even though thegarment should preferably ultimately be sized to fit on a smaller regionsuch as around the neck. In another example, a pair of pants includes aportion that is worn around the user's ankles or calves, but the entiregarment must be stretchable to fit over the user's foot, which has amuch larger cross-section.

Thus conventional under-sized garments relying solely on elasticity toprovide desired compression must overcome several obstacles in order tobe useful. The tension properties or stiffness of the elastane must behigh enough to provide the desired compression while still remainingloose enough that the garment can be stretched during donning or doffingof the garment. Elongation of a passive knit material has been studied,and is typically measured after pretensioning with a low amount offorce, such as 0.5N. In order to achieve this goal, conventionalcompression garments can incorporate high-elongation fabrics as well asany of a number of fasteners such as zippers, snaps, or ties that can befastened after the garment has been positioned on the user's body toincrease the compression on a desired region.

FIG. 2 shows a pneumatic garment 200 applied to a user's calf 202 and aportion of the user's foot 204. Pneumatic garment 200 is significantlybulkier than under-sized compression garment 100 of FIG. 1. Pneumaticgarment 200 is capable of providing controlled and variable amounts ofpressure, unlike under-sized compression garment 100 of FIG. 1.Pneumatic garment 200 of FIG. 2 includes a set of controls 206 that canbe manipulated to increase or decrease the applied pressure. By pumpingair into pneumatic garment 200, the thickness of the garment isincreased and pressure on the calf 202 and/or foot 204 is increased.

Unlike under-sized compression garment 100, pneumatic garment 200 iscapable of increasing or decreasing pressure during use. Pneumaticgarment 200 also adjusts somewhat for changes in circumference of thebody part that can result from sitting, standing, lying down, or othermovements or changes in position. Pneumatic garment 200 is substantiallyheavier and bulkier than under-sized compression garment 100, as itincludes controls 206 and associated pumps, valves, sensors, and powerstorage such as a battery necessary to transfer and hold air atabove-atmospheric pressure.

Therapeutic Compression Garments

FIGS. 3-8 relate to therapeutic compression garments.

FIG. 3 is a chart of a theoretical model for the force and length of atherapeutic compression garment. Force applied to the fabric or garment,shown on the y axis, can be used to determine a total tension using atensile test that measures a fabric's tension (T) at specific lengths,

T=F/w

where the recorded force (F) is divided by the measured fabric width(w). By determining the tension values of the fabric, the pressureexerted by the fabric on a body can be determined for specific fabriclengths. In one example, an orthostatic intolerance lower body garmentexerts between about 6 mmHg and about 77 mm Hg (about 800 Pa and about12 kPa) on the body. The range of fabric tensions required for thisgarment can be determined using the Hoop Stress formula, Laplace'sformula, and Macintyre's formula:

Hoop Stress formula:

δ_(θ) =F/tw

-   -   where δ_(θ)=hoop stress, F=force in N, t=fabric thickness in m,        w=fabric width in meters.

Laplace's formula:

P=(tδ _(θ))/r

where P=pressure in Pa, t=fabric thickness in m, δ_(θ)=hoop stress,r=limb radius in meters.

Macintyre's modified formula:

P=(t(F/tw))/r,

-   -   i.e., P=(F/w)/r, because T=F/w and the t's cancel out;    -   i.e., P=T/r

where P=pressure in Pa, T=fabric tension in N/m, r=limb radius inmeters.

Anthropometric data can be gathered to determine the limb radius. Theanthropometric data can be specific to a patient, or in embodimentsstandard or common sizes can be used to generate garments that areappropriate for many wearers. In this example, if the average leg radiusis 0.049 meters,

Lowest pressure:

${{799.9\mspace{14mu}{Pa}} = \frac{T}{0.049\mspace{14mu} m}},$

then T=799.9 Pa*0.049 m, then T=39 N/m

Highest pressure:

${{10265.8\mspace{14mu}{Pa}} = \frac{T}{0.049\mspace{14mu} m}},$

then T=10265.8 Pa*0.049 m, then T=503 N/m.

So to provide the desired level of compression, the fabric shouldexhibit tensions levels between 39 and 503 N/m.

Returning to FIG. 3, at 300 the therapeutic garment is an undersizedgarment in the martensite state. No force is being applied by or to thegarment. At 302, some force is applied to the garment to stretch it overthe user. The garment remains in the unactivated martensite state, sothe length of the garment increases along the bottom curve in FIG. 3 asforce is applied to stretch the garment.

Once the garment is donned, the garment relaxes as shown at 304, andforce applied returns to about zero while length is somewhat greaterthan the original length at 300. This is different from passive garmentssuch as the elastic garment shown in FIG. 1, which maintain somenon-zero force on the wearer at all times upon being stretched.

At 306, the fabric that makes up the garment is actuated, such as byapplication of heat. This actuation, or transition from martensite toaustenite phase, causes an increase in applied force (i.e.,compression), even though there is little to no change in the length ofthe fabric. The garment size enters a “blocked state” in which it cannotmove, but force increases.

The garment can be changed back to martensite to be removed, or inembodiments the state of the fabric can be alternated between austeniteand martensite to provide pressure pulses or other therapy, as describedin more detail below.

FIGS. 4A and 4B are plan views of fabric 400 made of a series of rows ofweft knit active yarns in relaxed and contracted states, respectively,according to an embodiment. Fabric 400 includes five rows (402A, 402B,402C, 402D, 402E) of an active yarn material. The term “active yarnmaterial” can refer to any thread, strand, filament, braid, or bundle ofmaterials that responds to thermal or electrical stimulation to changefrom a relaxed state to an activated state. In embodiments, braided orcoaxial bundles can provide a relatively higher level of strength thanindividual filaments and can also provide more force when switchingbetween relaxed and activated states.

The active yarn material that makes up each of the rows 402A, 402B,402C, 402D, 402E can comprise a shape memory alloy (SMA). Inembodiments, the SMA can be a type of active metal with pseudoelasticproperties that is highly malleable in a cool, martensite phase and hasshape recovery abilities, even under load, during the elastic austenitephase. In one embodiment, the active yarn material can be a nitinolmaterial. SMAs can be engineered to switch from martensite to austenitedepending on whether they are above or below a transition temperature.

SMAs can be engineered to exhibit desired properties by altering thematerial composition and the heat treatments. Specifically, stress,strain, recovery, and activation temperature are functional propertiesthat can be manipulated through the thermomechanical manufacturingprocess. Consequently, SMAs can be designed to activate at specifictemperatures to require relatively low power consumption and temperatureloads on the body compared to powered, pneumatic systems.

Knit structures such as fabric 400 can be used in large, complexstructures that are actuated across complex surfaces (such as thesurface of the body). The variety of structures that can be created withinterlocking loops or stitches within each row (e.g., rows 402A, 402B,402C, 402D, 402E) and the shape change that occurs when these loops aresubject to tension can be customized to the contours of a particularbody part such as a leg or arm.

Knitting can be divided into two general architectures: (1) weftknitting, which is a process in which an individual end of yarn is fedinto or knit by one or more needles in a crosswise (lateral) fashion,and (2) warp knitting, which is a process in which a multiplicity ofyarns are fed into or knit by one or more needles in a lengthwise(vertical) fashion. While weft knits have more mechanical stretch, warpknits are often more stable architectures and can be constructed usingmany wales, or columns, of yarn. Additional yarns can be introduced intoweft knit structure by utilizing a jacquard system, which selectivelyengages and disengages needle beds to form a knit pattern using multipleyarns. Warp knits can also achieve complex patterning through the use ofguide bars, which allow some warp knit structures (e.g., raschel knits)to appear like lace-structures. Hand-knitting (a weft knit structure),lace-making, crocheting, tadding, and needle-lace are other manualmethods of selectively looping yarns into a fabric structure. Complexpatterns can be achieved using other techniques such as hand-knitting,lace-making techniques, or others, which can be used to loop yarnsselectively into the fabric structure. Although FIGS. 4A and 4B depict asimple weft pattern, other embodiments can include a variety ofrelatively more complex knitting stitches and patterns including warpknitting, jacquard, intarsia, Fair Isle, or any other knitting patternand combinations thereof.

FIG. 4B shows the same five rows 402A, 402B, 402C, 402D, 402E of activematerial described above with respect to FIG. 4A, but in FIG. 4B therows 402A, 402B, 402C, 402D, 402E are in a compressed state indicated byarrows. Fabric 400 can change from the relaxed state shown in FIG. 4A tothe compressed state shown in FIG. 4B due to a change in temperature.For example, the active material can have a transition temperature, andonce each of the rows 402A, 402B, 402C, 402D, 402E becomes hotter thanthat transition temperature the active material can transition frommartensite to austenite, and vice versa.

As shown in FIGS. 4A and 4B, depending upon the state of the rows of anactive material, the overall width of the fabric can vary. Width of anactive fabric can be relatively wider in the relaxed state, andrelatively narrower in the activated state. A user can change betweenthese two states by heating or cooling the rows. To heat the rows,electrical current can be routed through some or all of the rows.Alternatively, an adjacent liner can provide heat or cooling to fabricto cause it to change between activated and relaxed states.

A fabric made of a shape memory alloy or other active knit material canbe modified to form other fabric types or patterns by changing any of atleast five features. First, the relative number of active yarns topassive yarns (as described in more detail below with respect to FIGS.5A-5C) can be varied to provide different levels and targeted areas ofcompression. Second, the stitch size or relative density (i.e., gauge)of the stitches can be modified to affect the knit index i_(k). Third,current and voltage (or power dissipation) through the active yarns canbe controlled to affect activation of each of the active yarns. Fourth,the weight or diameter of the yarn (which can be either a singlefilament or a bundle of active filaments) can be modified, with thickeryarns generally providing a higher level of compression upon activation.Finally, the transition temperature of the active yarns can vary betweenembodiments, and in fact within segments of the same fabric, to createzones as described in more detail below. Zones that have differenttransition temperatures will activate at different times, even underuniform heating or cooling.

FIGS. 5A and 5B are plan views of fabric 500. Fabric 500, like fabric400 of FIGS. 4A and 4B, includes five rows (502A, 502B, 502C, 502D,502E) of knitted material. Fabric 500, unlike fabric 400, includesmultiple knitted materials in alternating rows. Shaded rows 502B and502D are an active yarn material, similar to the material that makes upactive rows 402A-402E described above with respect to FIGS. 4A and 4B.In contrast, rows 502A, 502C, and 502E are made of a passive materialthat does not transition between martensite and austenite states. Apassive material can be non-conductive such that electrical heating willnot occur in a passive material. For example, the passive material couldbe a non-conductive polymer. A non-conductive polymer will not drawpower when a voltage source is attached to it, therefore use of passivezones in a fabric (e.g., fabric 500) can reduce overall powerdissipation per unit area.

Consequently, while in the relaxed state fabric 400 of FIG. 4A lookssubstantially the same as fabric 500 of FIG. 5A. In contrast, in theactivated state fabric 400 (shown in FIG. 4B) compresses by a greateramount than fabric 500 (shown in FIG. 5B, compression indicated byarrows). That is, the proportional difference between width 406 andwidth 406′ is larger than the difference between width 506 and width506′.

FIGS. 6A, 6B, and 6C are plan views of three weft knitting patternsincluding active and passive sections.

As shown in FIG. 6A, fabric 600A includes two active sections A1 and A2,as well as three passive sections P1, P2, and P3. Active sections A1 andA2 are each made up of six rows of active knitted material, describedabove with respect to FIGS. 4A, 4B, 5A, and 5B. Fabric 600 is shown inthe relaxed state. By applying heat to active section A1 and/or activesection A2, the width 606A of fabric 600A can be reduced.

The maximum possible extent of the reduction in width varies based uponthe number of rows of knitted material within each active section (A1,A2) and the number of rows within each passive section (P1, P2, P3), inaddition to the factors described above (i_(k) and d) that affectactuation contraction. Likewise, the maximum possible pressure dependson the applied force F_(app) as described above. For a therapeuticcompression garment, the applied force is often relatively high whilethe total actuation contraction is low, which can be facilitated by theuse of passive sections P1-P3 interspersed with active sections A1 andA2 that provide strong contraction over a short distance.

In the embodiment shown in FIG. 6A, each active section A1, A2 includessix rows, whereas each passive section P1, P2, P3 includes two rows ofpassive material. Therefore 75% of the rows within fabric 600A can beactivated to cause compression. In alternative embodiments such as thoseshown in FIGS. 6B and 6C, where different portions of the fabric areactive or passive, the length can remain constant in passive regionswhile varying due to activation of the active regions as described inthe equations above.

Active sections A1 and A2 can be activated independently of one another.For example, in embodiments fabric 600A can be activated by applying anelectrical current through active sections A1 and A2 to cause heating.In some cases it may be desirable to activate less than the full 75% ofthe rows. For example, if it is desirable to activate only 37.5% of therows, either active section A1 or active section A2 could be activated,leaving the other in the passive state.

FIG. 6B is an alternative embodiment in which fabric 600B includesactive sections A3 and A4, as well as passive sections P4, P5, and P6.Like fabric 600A, fabric 600B includes active sections A3 and A4 thateach include six rows of an active or shape-memory material. Fabric 600Bhas relatively wider passive sections P4, P5, and P6 than thecounterpart passive sections P1, P2, and P3 of FIG. 6A. In particular,passive sections P4, P5, and P6 each have four rows, in contrast to the2-row passive sections P1, P2, and P3 of FIG. 6A. The percentage of rowsthat are active in fabric 600B of FIG. 6B is therefore 60%, compared to75% that are active in fabric 600A of FIG. 6A.

FIG. 6C is an alternative embodiment in which fabric 600C includesactive sections A5 and A6, as well as passive sections P7, P8, and P9.Active sections A5 and A6 each include four rows of an active orshape-memory material, while passive sections P7, P8, and P9 eachinclude four rows of a passive material. The percentage of rows that areactive in fabric 500C of FIG. 7C is therefore 50%, compared to 75% thatare active in fabric 700A of FIG. 6A or 60% in fabric 600B of FIG. 6B.

FIGS. 7A, 7B, and 7C are front, back, and side perspective views of atherapeutic compression garment 800 according to an embodiment.Therapeutic compression garment 700 includes three sections, 702A, 702B,and 702C. Each of the sections 702A-702C is made up of a differentcomposition of active and passive material. Therefore the level ofcompression in each section 702A-702C is different, because each section702A-702C will contract by a different amount when the active sectionstherein are activated. Compression levels can be targeted to areas whereit desirable to apply relatively higher or lower amounts of compression.The different compositions in each section can be, for example,different knit tightness or pattern (affecting i_(k)), differentdiameter of knit material (affecting d), different ratios of active topassive materials, or the use of different materials that have differentshape memory characteristics such as transition temperature, transitiondisplacement, or transition force.

FIG. 7B shows connector 704. In embodiments, connector 704 can be azipper, a pair of hook-and-loop connectors, snaps, buttons, or otherfasteners to couple the edge of garment 700 to another edge or portionof garment 700 to form a closed loop or sleeve. In alternativeembodiments, connector 704 may not be required. Depending on the size ofthe loops that make up each of the active and passive rows, as well asthe thickness of the material, some embodiments of garment 700 are looseenough to be donned without a connector 8. Such embodiments can bepermanently sewn together, or other techniques such asknitting-in-the-round can be used to create those embodiments.

In alternate embodiments, the sections 702A-702C can have equalpercentages of active and passive material, but the sections 702A-702Ccan be operated differently. For example, half of the active sections ofone zone may be activated, while three quarters of the active zones ofanother zone are activated, and all of the active zones of the thirdzone are activated. Compression gradients can be created in this waywithout customizing the knitting pattern of the garment.

In alternate embodiments, zones need not be circular and extendlongitudinally. Instead, zones could be arranged at different azimuthalpositions within a cylindrical section, or zones could be any otherirregular shape that can be knitted into the overall fabric. Activesections can be concentrated in areas where compression is desired, ashigher concentrations of active regions can be used to focus thecompression to those areas.

FIG. 7D is a plan view of garment 700, laid out flat with connector 704disconnected. As shown in FIG. 7D, zone 702A has a relatively highpercentage of passive sections P (shown in light color), zone 702B has aslightly lower percentage of passive sections P, and zone 702C has thelowest percentage of passive sections P (and, correspondingly, thehighest percentage of active sections A).

Other garments can be configured to adapt compression levels based onthe body's dynamic shape change. For example, a garment with an activematerial architecture can be designed to dynamically expand incircumference from 1 to 6% at the calf and from 1 to 8% at the anklewhen the wearer transitions from a standing to a seating posture toaccommodate anthropometric changes and maintain a target pressureoutput. A garment for use on a knee region can take into accountincreasing radii to prevent tourniquetting of blood into the feet andcalves. An active architecture can expand up to 7% at the knee whensitting, in an embodiment, up to 12% in other embodiments, or up to 13%in alternative embodiments. For thigh compression, the active materialarchitecture can expand or contract from a target standingcircumference. To accommodate the anthropometric requirement of thethigh, an active material designed for the thigh region can have agreater circumferential stroke change than other regions of the leg.Like the knee, the thigh region requires the design of several differentactive architectures according to weight category. In some embodiments,the total amount of compression can correspond to a circumferentialchange up to 14% in some embodiments, up to 15% in other embodiments, upto 16% in still further embodiments, and up to 17% in still furtherembodiments. In other embodiments, tourniquetting of the blood can bedesirable, and therefore the amount of compression applied to aparticular region may exceed the amount that permits normal blood flow.

Active materials can be selected that have transition temperatures nearthe ambient temperature of areas where they will be used. For example,compression garments could have active zones knitted from an activematerial that has a transition temperature slightly higher than skintemperature. Very little additional energy is then required to cause thematerial to change to the activated state, and no energy is required tocool the active material back below its activation temperature.Transition between states can also be rapid as the total amount oftemperature change required to transfer between the states is small.

In embodiments, the level of compression provided by a garment or even aparticular zone within a garment can vary over time. For example, powercan be supplied to active materials to cause heating and activation,then power can be stopped and the material allowed to cool, at a desiredfrequency. Entire zones can be pulsed in this way, and pulsing ofdifferent zones can be coordinated. Coordination of pulsed pressureapplication can be used, for example, to promote lymph flow or bloodcirculation. In embodiments, sensors can be used to detect attributes ofthe patient. For example, sensors can detect a pulse rate of a patient,and pulsing of the power supply can correspond to that pulse rate inorder to promote circulation. A control system, either with or withoutsensors, can be used to set the pulse rate, compression amount, or otheraspects of the garment.

In embodiments where more rapid pulsing is required, or where theactivation temperature of the active material is close to the ambientconditions where that garment will be used, active cooling can beemployed to more rapidly convert the material back to its relaxed state.For example, a sleeve can surround the active material in a garment, andthe sleeve can act either as a heat sink or can be actively chilled.

Other sleeves and liners that promote comfort or ease of use of thegarment can be used. In one embodiment, an inner sleeve of a smoothmaterial is attached to the active and passive material zones. The innersleeve acts as a barrier to prevent contact of the fabric (e.g., fabric400, 500) with the user. Inner and outer sleeves or liners can includemedicaments or other substances, in embodiments.

As shown in FIG. 8, a multi-layer garment 800 can include four separatecompression layers 802A, 802B, 802C, and 802D, arranged between a topliner 804 and a bottom liner 806. Each compression layer 802A-802D ismade up of active material 808 and passive material 810. Active material808 and passive material 810 can be knitted together as described above.Multiple layers 802A-802D can be used to generate more compressive forcethan a single layer, which can be beneficial depending upon thecompressive strength of the active material 808 and the amount ofcompression desired.

In embodiments, top liner 804 can be connected to the closestcompression layer 802A. The connection can be either continuous (i.e.,interwoven), or in embodiments top liner 804 can be loosely connected tocompression layer 802A. Likewise, bottom liner 806 can be either tightlyor loosely coupled to compression layer 802D. In alternativeembodiments, active regions 808 or each layer (802A, 802B, 802C, 802D)need not align with one another in regular columns as shown in FIG. 9.Rather, the active regions 808 could be staggered, or could be sized andpositioned differently between each of the layers (802A, 802B, 802C,802D).

Self-Fitting Garments

FIGS. 9-15B relate to self-fitting garments.

Self-fitting garments rely on the same underlying principles oftransition from martensite to austenite and back that are describedabove with respect to therapeutic compression garments. In self-fittinggarments, however, the goal is often to have the garment shrink to sizefor a wearer, without applying any constrictive force.

As described above, in knitted active materials a relevant parameterthat affects the overall compression provided by a knitted segment isdefined by the ratio of the loop area enclosed in the martensite state(A_(l, m)) and the square of the active knit material wire diameter d:

i _(k) =A _(l,m) /d ².

It should be understood that in embodiments it may be desirable to use athread or yarn of active materials, or a twisted pair or trio of wires,or any of a variety of braids, for example, and the equations hereinapply to the idealized case. Each alternative configuration will havedifferent compression characteristics, which are not described in detailwithin this disclosure.

In the idealized case of knit material with circular cross sections, theknit index i_(k) is an intuitive and easily obtainable parameterdescribing the dimensionality of contractile SMA knitted actuators. Alow knit index corresponds to densely knitted fabrics, with a relativelyhigh proportion of active material in a unit area.

FIG. 9 is similar to FIG. 3 in that it shows force and length for anactive fabric. Unlike FIG. 3, though, FIG. 9 depicts the change inlength and force for a self-fitting garment. In general, as describedabove, self-fitting garments aim to provide more displacement and lessforce, to provide a garment with little or no “ease” (i.e., little or nodifference in circumference of the garment compared to the circumferenceof the body part it covers).

At 900, an oversized, martensite garment is provided. As the garment isdonned at 902, some force is applied to stretch the garment. Oncedonned, the martensite garment relaxes on the body, such that no forceis applied as shown at 904. As the garment is heated it transitions toaustenite, causing contraction of the fabric. At first, this contractiondoes not cause any force to be applied, until the garment reaches thesame circumference as the body part it covers at 906. Thereafter, if thegarment may continue to apply some force as shown at 908.

FIGS. 10A-10C depict three styles of garments that show the benefit of aself-fitting garment. An inelastic fabric garment such as garment 1002shown in FIG. 10A is loose fitting, and leaves room between the leg andthe garment 1002. An inelastic fabric garment 1004 of FIG. 10B can bemade to be form fitting, but in order to be donned a fastener 1004(here, a zipper) is required. In order to avoid the use of fastener1004, a stretch fabric is used in garment 1006 to constrict the garment.For most wearers, the inelastic garment 1002 is the easiest to don ordoff. Meanwhile, 1004 is the most appropriately sized for wearing, as itis neither constrictive nor baggy, but it suffers from the requirementof fasteners if it is made of an inelastic fabric. Forgoing theinelastic fabric of FIG. 10B and instead relying on elastic constrictionof the elastic garment 1006 of FIG. 10C creates its own issues, such asoverly constrictive garments and difficulty donning and doffing thegarment 1006 as compared to an inelastic fabric such as those used ingarments 1002 and 1004.

The required fit for various garments varies. For example, oversizedt-shirts designed in three sizes may fit a larger portion of thepopulation than a fitted dress shirt in six sizes due to the amount ofgarment ease that is aesthetically desired in that garment. In mostgarments that are not used for therapeutic compression, however, zeroease (or near to zero ease) is desirable for comfort and aesthetics.

FIGS. 11A-11D depict a self-fitting garment that has approximately zeroease without the use of fasteners, according to an embodiment. As shownin FIG. 11A, the proposed garment 1100 is compliant and oversized beforedon (i.e., at stage 900 of FIG. 9). During the donning process, as shownin FIG. 11B the compliant garment 1100 is stretched out further as it ispulled over the limbs (i.e., at stage 902 of FIG. 9). Once on the bodyand free of external forces, the garment slightly relaxes around its newform as shown in FIG. 11C (i.e., at stage 904 of FIG. 9). The garmentthen warms to skin temperature, which causes the shape memory alloymaterials that are knitted into garment 1100 to contract and stiffen asshown in FIG. 11D (i.e., to stage 906 and then 908 of FIG. 9). Theresult is a non-elastic, not stretchy garment with zero or near-zeroease. To doff, the garment would either need to be cooled or designedwith release mechanisms.

Although garment 1100 is shown as a pair of pants, other garments can bemade that will conform similarly. For each type of garment, aself-fitting garment can be designed by mapping the body-garmentrelationship. Contractile SMA knitted actuators exhibit tunablefunctional performance through the systematic modification of geometricdesign parameters, specifically wire diameter d and knit index i_(k), asdescribed above. Before determining suitable knit geometries to achieveself-fit, the body-garment relationship can be mapped. Mapping can beaccomplished by gathering dimensional data from a sample group. Markscan be placed on the participants' body and at each incremental mark, acircumferential measurement is taken.

Once circumferential measurements have been gathered, the performancerequirements of the self-fitting garment can be compared with themeasurements to design a garment. For an inextensible garment such asgarment 1100, the minimum garment dimension required at the base of apant leg to enable don/doff (i.e., traverse the foot) was determined tobe the calf dimension plus 2.5 cm of positive ease. This recommendedadded garment dimension means that the garment circumference around theankle should be equal to the garment dimension around the calf.Additionally, the garment 1100 dimension around the knee must be equalto the garment dimensions around the calf to enable the garment totraverse the calf. The required functional performance of theself-fitting garment is consequently defined as the percentualdifference between the garment dimensions and the body dimensions. Thecircumference of the body and the garment are shown in the left-handside of the graph in FIG. 12. Based on the initial and desiredcontracted circumference at each portion on the body (i.e., the initiallength and contracted length of each circumferentially-extending shapememory coil), the required contraction ζ_(req) can be determined.

For garments that are designed primary for comfort and aesthetics (i.e.,where desired compression is near zero rather than a positive value),actuation contraction ζ_(req) should ordinarily be maximized while theforce applied F_(app) should be minimized, while still maintainingdesired contraction under forces that are to be expected during wear.FIG. 13 shows a martensite-austenite transition loop corresponding to anembodiment. Upon donning the fully-martensitic garment at (1), smallforces are exerted on the garment, which cause further garmentdimensional expansion at (2). Upon release, the garment contracts intoits martensite relaxed state and recovers some of the extension from thedonning process (3). Heating (body or external source) causes thegarment circumference to decrease to approximate the leg circumferenceat (4). Additional contractile ability of the garment results in ageneration of forces and pressure on the leg, which are to be minimizedin the design (though as described above with respect to therapeuticcompression garments this may not always be the case).

FIG. 13 illustrates a flowchart of a method according to an embodiment.At 1300, anthropometric data is provided, such as from a database orfrom independent measurements of a body part for which a garment isbeing created. At 1302, the anthropometric data is used to calculatedonning and doffing ease for N different body cross sections orcircumferential measurements, as described above with respect to FIG.12. At 1304, the ideal circumference for each of these N circumferentialbody cross-sections is determined. At 1306, for each body cross-sectionsn of the N total body cross-sections, an actuation contraction ζ isdetermined. If the actuation contraction ζ is too large (i.e., greaterthan the required actuation contraction ζ_(req)), then the circumferencefor that knitted garment cross-section is recalculated (i.e. number ofknit courses is added or subtracted) or another knitted architecture isselected. Otherwise, the pressure applied by that knitted architectureat a certain length (i.e. number of knitted courses) is calculated at1308. The pressure applied by a knitted cross-section n is directlyrelated to the force applied F_(app). If the force is too great (e.g.,more than 1333 Pa in some embodiments, or greater than 1000 Pa in otherembodiments), then the circumference for that knitted cross-section isrecalculated (i.e. number of knit courses is added or subtracted).Otherwise, the difference between the diameter of the wire used inknitted cross-section n and the diameter of the wire used in precedingknitted cross-section n−1 is determined. If that difference is greaterthan a threshold (e.g., 0.1 mm) then another knitted architecture isselected. Otherwise, the knitted architecture and the number of coursesthat make up that knitted cross-section n is finalized and the processis iterated through the remainder of the N cross-sections at 1312. Onceall of the cross-sections from 1 to N are calculated, the design iscomplete.

FIGS. 14 and 15 show test data for a series of fabrics made withdifferent knit indices and diameters.

FIG. 14A shows applied load vs. actuation contraction for a series ofloops of shape memory alloy material, all of which have a knit index of65, but which have varying diameters. FIG. 14B shows mechanical work asa function of applied load for the same loops as FIG. 14A.

FIG. 14C shows applied load vs. actuation contraction for a series ofloops of shape memory alloy material, all of which have a knit index of130, but which have varying diameters. FIG. 14D shows mechanical work asa function of applied load for the same loops as FIG. 14C.

FIGS. 15A and 15B show applied load as a function of actuationcontraction, and mechanical work as a function of applied load,respectively. Each of the lines depicted in FIGS. 15A and 15Bcorresponds to a shape memory coil having a diameter of 0.203 mm, buteach of the lines has a different knit index, varying from 39 to 138. Asshown in FIGS. 14A-14D and 15A-15B, a maximum actuation contractionpoint can be determined for each index and diameter. The maximumactuation contraction is a very useful and widely used metric for theanalysis of the actuation performance of uniaxial actuators. The appliedload over actuation contraction profiles of contractile SMA knittedactuators share the characteristic shape with a deflection point at themaximum actuation contraction. Under loading conditions below themaximum actuation contraction, the behavior of the knitted actuator isdominated by the variable stiffness upon phase transformation, whichleverages the geometry to achieve constantly increasing actuationcontractions. At applied loads larger than the force at maximumactuation contraction, the knitted architecture loses the ability torecover the deformations, which results in decreased actuationcontractions. The maximum actuation contraction ζ is obtained bydetermining the global maxima of (l_(M)−l_(A))/l_(M), as describedabove.

Various embodiments of systems, devices, and methods have been describedherein. These embodiments are given only by way of example and are notintended to limit the scope of the claimed inventions. It should beappreciated, moreover, that the various features of the embodiments thathave been described may be combined in various ways to produce numerousadditional embodiments. Moreover, while various materials, dimensions,shapes, configurations and locations, etc. have been described for usewith disclosed embodiments, others besides those disclosed may beutilized without exceeding the scope of the claimed inventions.

Persons of ordinary skill in the relevant arts will recognize that thesubject matter hereof may comprise fewer features than illustrated inany individual embodiment described above. The embodiments describedherein are not meant to be an exhaustive presentation of the ways inwhich the various features of the subject matter hereof may be combined.Accordingly, the embodiments are not mutually exclusive combinations offeatures; rather, the various embodiments can comprise a combination ofdifferent individual features selected from different individualembodiments, as understood by persons of ordinary skill in the art.Moreover, elements described with respect to one embodiment can beimplemented in other embodiments even when not described in suchembodiments unless otherwise noted.

Although a dependent claim may refer in the claims to a specificcombination with one or more other claims, other embodiments can alsoinclude a combination of the dependent claim with the subject matter ofeach other dependent claim or a combination of one or more features withother dependent or independent claims. Such combinations are proposedherein unless it is stated that a specific combination is not intended.

Any incorporation by reference of documents above is limited such thatno subject matter is incorporated that is contrary to the explicitdisclosure herein. Any incorporation by reference of documents above isfurther limited such that no claims included in the documents areincorporated by reference herein. Any incorporation by reference ofdocuments above is yet further limited such that any definitionsprovided in the documents are not incorporated by reference hereinunless expressly included herein.

For purposes of interpreting the claims, it is expressly intended thatthe provisions of 35 U.S.C. § 112(f) are not to be invoked unless thespecific terms “means for” or “step for” are recited in a claim.

1. A therapeutic garment configured to provide compression in a radialdirection, the therapeutic garment comprising: a plurality of knittedrows of an active material each extending in an axial direction, each ofthe rows having a plurality of loops of the active material to define aknit index, wherein each of the plurality of loops of the activematerial defines a cross-sectional diameter, and wherein the knit indexand the cross-sectional diameter are selected to provide a therapeuticlevel of applied force by the active material due to a thermaltransition in the active material.
 2. The therapeutic garment of claim 1wherein the garment further comprises a plurality of knitted rows of apassive material that extend axially along the therapeutic garment. 3.The therapeutic garment of claim 1, further comprising a fastener. 4.The therapeutic garment of claim 1 wherein the therapeutic garment is acompression sock having a open end and a closed end, wherein the fibersextend along the axial direction between the open end and the closedend.
 5. The therapeutic garment of claim 1 wherein the compression upontransition of the active material causes first level compression at afirst portion along the axial direction and a second level ofcompression at a second portion along the axial direction, and whereinthe first level of compression is different from the second level ofcompression.
 6. The therapeutic garment of claim 5 wherein the firstlevel of compression and the second level of compression arepredetermined to provide a therapy.
 7. The therapeutic garment of claim1 wherein the active material is configured to provide pulsed pressureoutput.
 8. The therapeutic garment of claim 1 wherein the activematerial is heated by an electrical power source.
 9. The therapeuticgarment of claim 1 wherein the active material has a transitiontemperature that is between a room temperature of about 20° C. and askin temperature of about 30° C.
 10. The therapeutic garment of claim 1wherein the active material has a transition temperature that is betweena freezer temperature of about −15° C. and a skin temperature of about30° C.